Evaluation of Root Dentin Cracks Caused by Three Single File Systems Versus Pro Taper System – An In Vitro Study

Introduction: Biomechanical preparation of root canals isone of the main steps in achieving endodontic success dueto enabling bacterial elimination, removal of debris, andfacilitating obturation. The aim of this study was to comparethe incidence of dentinal cracks observed in the canal wallafter canal instrumentation with 3 single-file systems and theProTaper system (Dentsply Maillefer, Switzerland).Material and Methods: Eighty mandibular premolars withsingle root canal were selected. Teeth were decoronated andmounted in resin blocks with simulated periodontal ligaments.They were divided into 4 experimental groups (n = 20); theninstrumented to the full working length with the ProTaper,OneShape (MicroMega, Besancon, France), Reciproc (VDW,Munich, Germany), and WaveOne Gold (Dentsply Malliefer)was performed. The roots were sectioned perpendicular to thelong axis at 3, 6, and 9 mm from the apex and were observedunder a stereomicroscope. The presence of cracks was noted.The chi-square test was performed to compare the appearanceof cracked roots between the experimental groups.Results: Cracks found after canal instrumentation with theProTaper, OneShape, and Reciproc and WaveOne Goldfiles, were 46.6%, 23.3%, 13.6%, 11.6% respectively. Thedifference between the experimental groups was statisticallysignificant (P < .001).Conclusion: Nickel-titanium instruments cause cracks in rootsurface or in the canal wall; Reciproc and WaveOne Gold filescaused less cracks than the ProTaper and OneShape files.

Evaluating the cutting efficiency of NiTi instruments with reciprocating motions / Avaliação da eficiência de corte de instrumentos NiTi com movimento reciprocante

Aim:This study tested a setup for in vitro experimental analysis of axial forces and torque during the preparation of artificial canals using nickel-titanium reciprocating endodontic files.Methods: The cutting efficiency of Reciproc (RC) and WaveOne (WO) reciprocating size 25/.08 instruments (n = 10) was evaluated, taking into account their dimensional and geometrical features. Measurements of the diameter at each millimeter from the tip, pitch length, helical angle, and cross-sectional design and area were assessed. Cutting efficiency tests were carried out on a specific bench device by measuring the torque and axial force required during artificial canal shaping. Statistical analysis was performed using one-way ANOVA (α = 0.05). Results:The WO samples showed larger A3 mean values than did the RC instruments (p < 0.0001), despite having equal diameters at 3mm from the tip (D3) (p = 0.521). The mean values of pitch length were higher for RC than for WO instruments (p< 0.0001), with consequently smaller helical angles (p < 0.0001). For the cutting efficiency tests, the required torque was lower for the RC group when compared to the WO group, but it was significant only in the first stage of insertion in the artificial canals (p = 0.008). Regarding the apical force, the RC instruments reached higher values when compared to the WO instruments (p = 0.04) in the second stage of cutting action. Conclusion: Reciproc instruments demonstrated statistically higher cutting efficiency when compared to WaveOne instruments.

Objetivo: Este estudo testa uma configuração para análise experimental in vitro de forças axiais e torque durante o preparo de canais artificiais usando instrumentos endodônticos reciprocantes de níquel-titânio. Métodos: Foi avaliada a eficiência de corte dos instrumentos reciprocantes tamanho 25 / 0,08 (n = 10) Reciproc (RC) e WaveOne (WO), levando em consideração suas características dimensionais e geométricas. Medidas do diâmetro a cada milímetro a partir da ponta, comprimento de pitch, ângulo helicoidal e desenho da área transversal e área foram avaliados. Testes de eficiência de corte foram realizados em um dispositivo de bancada específico, medindo-se o torque e a força axial exigidos durante a modelagem de canais artificiais. A análise estatística foi feita com ANOVA one-way (α = 0,05). Resultados: As amostras de WO mostraram valores médios A3 maiores do que os instrumentos RC (p <0,0001), apesar de terem diâmetros iguais a 3 mm da ponta (D3) (p = 0,521). Os valores médios do comprimento do pitch foram maiores para o RC do que para os instrumentos do WO (p < 0,0001), com consequentemente menores ângulos helicoidais (p < 0,0001). Para os testes de eficiência de corte, o torque necessário foi menor para o grupo RC em comparação com o grupo WO, mas significativo apenas no primeiro estágio de inserção nos canais artificiais (p = 0,008). Em relação à força apical, os instrumentos RC alcançaram valores maiores em relação aos instrumentos WO (p = 0,04) no segundo estágio de corte. Conclusão: Os instrumentos Reciproc demonstraram uma eficiência de corte estatisticamente superior em comparação com os instrumentos WaveOne.

Protaper Next: la evolución / Protaper Next: the evolution

El objetivo del presente artículo es describir y analizar las características técnicas y de diseño del sistema Protaper Next. Este sistema aparece en el mercado odontológico en el año 2012, transformándose en el sucesor del Protaper Universal. Una de sus principales modificaciones consiste en la disminución del número de instrumentos requeridos para realizar el tratamiento endodóntico.

The objective of this article is to describe and analyze the technical and design characteristics of the Protaper Next System.This system appeared at the dental market in 2012 becoming the successor of Protaper Universal.One of its main modifications is the minor numbers of instruments required for doing an endodontic treatment.

The effects of autoclave sterilization on the cyclic fatigue resistance of ProTaper Universal, ProTaper Next, and ProTaper Gold nickel-titanium instruments

OBJECTIVES: It was aimed to compare the cyclic fatigue resistances of ProTaper Universal (PTU), ProTaper Next (PTN), and ProTaper Gold (PTG) and the effects of sterilization by autoclave on the cyclic fatigue life of nickel-titanium (NiTi) instruments. MATERIALS AND METHODS: Eighty PTU, 80 PTN, and 80 PTG were included to the present study. Files were tested in a simulated canal. Each brand of the NiTi files were divided into 4 subgroups: group 1, as received condition; group 2, pre-sterilized instruments exposed to 10 times sterilization by autoclave; group 3, instruments tested were sterilized after being exposed to 25%, 50%, and 75% of the mean cycles to failure, then cycled fatigue test was performed; group 4, instruments exposed to the same experiment with group 3 without sterilization. The number of cycles to failure (NCF) was calculated. The data was statistically analyzed by using one-way analysis of variance and post hoc Tukey tests. RESULTS: PTG showed significantly higher NCF than PTU and PTN in group 1 (p < 0.05). Sterilization significantly increased the NCF of PTN and PTG (p < 0.05) in group 2. PTN in group 3 had significantly higher cyclic fatigue resistance than PTN group 4 (p < 0.05). Also, significantly higher NCF was observed for PTG in group 2 than in groups 3 and 4 (p < 0.05). CONCLUSIONS: PTG instrument made of new gold alloy was more resistant to fatigue failure than PTN and PTU. Autoclaving increased the cyclic fatigue resistances of PTN and PTG.

Finite Element Study on Continuous Rotating versus Reciprocating Nickel-Titanium Instruments

Abstract In the present study, GTX and ProTaper as continuous rotating endodontic files were numerically compared with WaveOne reciprocating file using finite element analysis, aiming at having a low cost, accurate/trustworthy comparison as well as finding out the effect of instrument design and manufacturing material on its lifespan. Two 3D finite element models were especially prepared for this comparison. Commercial engineering CAD/CAM package was used to model full detailed flute geometries of the instruments. Multi-linear materials were defined in analysis by using real strain-stress data of NiTi and M-Wire. Non-linear static analysis was performed to simulate the instrument inside root canal at a 45° angle in the apical portion and subjected to 0.3 N.cm torsion. The three simulations in this study showed that M-Wire is slightly more resistant to failure than conventional NiTi. On the other hand, both materials are fairly similar in case of severe locking conditions. For the same instrument geometry, M-Wire instruments may have longer lifespan than the conventional NiTi ones. In case of severe locking conditions both materials will fail similarly. Larger cross sectional area (function of instrument taper) resisted better to failure than the smaller ones, while the cross sectional shape and its cutting angles could affect instrument cutting efficiency.

Resumo As limas rotativas GTX e ProTaper foram comparadas numericamente com as limas reciprocatórias WaveOne pela análise de elementos finitos, com o objetivo de baixar custos, comparação fiel e exata, além de pesquisar o efeito do projeto das limas e de seu material sobre a durabilidade. Dois modelos tridimensionais de análise de elementos finitos foram especialmente elaborados para esta comparação. Utilizou-se um sistema de engenharia CAD/CAM comercial para construir o modelo totalmente detalhado da geometria das estrias das limas. Materiais multi-lineares foram definidos na análise usando dados reais de deformação por estresse de NiTi e M-Wire. Procedeu-se à análise estática não linear para simular a ação do instrumento dentro do canal radicular em ângulo de 45° na região apical, submetido a uma torsão de 0.3 N.cm. As três simulações realizadas no presente estudo demonstraram que o M-Wire é um pouco mais resistente a falhas que o NiTi convencional. Por outro lado, ambos os materiais são bastante similares em condições de travamento severo. No caso da geometria das limas, os instrumentos de M-Wire podem ter vida útil mais longa que os de NiTi convencional. Em condições de travamento severo, ambos os materiais terão falhas similares. Maior área transversal (em função da conicidade do instrumento) resiste melhor a falhas que as áreas transversais menores, ao passo que a geometria da área transversal e seus ângulos de corte podem afetar a eficiência de corte das limas.

Single file niti-rotary systems.

The cleaning and shaping of root canals is a major step in root canal treatment procedure, which aims at removal of all the tissue debris from the root canal space while removing the inner layers of root canal dentin. With Nickel titanium (NiTi) rotary instruments this goal is easier to achieve, even in curved root canals. The recently introduced Single file NiTi-rotary systems such as WaveOne, Reciproc, OneShape & F360 claim to be able to completely prepare and clean root canals with only one instrument. Use of single file rotary systems, are cost effective, time saving, reduce instrument fatigue and possible crosscontamination. The purpose of this article is to review single file Niti-Rotary systems for canal preparation.